


Children Know Better

by Kpop_personalities



Category: Haikyuu!!
Genre: Alpha Oikawa Tooru, Alpha Sawamura Daichi, Alpha/Beta/Omega Dynamics, Beta Iwaizumi Hajime, Child Kageyama Tobio, Happy Ending, Implied Mpreg, Implied/Referenced Sex, Light Angst, M/M, Omega Kageyama Tobio, Omega Sugawara Koushi, Tobio saves the day
Language: English
Status: Completed
Published: 2021-01-07
Updated: 2021-01-07
Packaged: 2021-03-18 06:53:55
Rating: Teen And Up Audiences
Warnings: No Archive Warnings Apply, Underage
Chapters: 1
Words: 3,797
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/28613907
Author URL: https://archiveofourown.org/users/Kpop_personalities/pseuds/Kpop_personalities
Summary: Iwaizumi always knew Tobio was an intelligent kid the moment he realized his baby was able to speak Japanese and Spanish way better than other kids his age. He didn’t know that this would lead him to make conclusions which would reveal his secret to the one person he had been avoiding for the past 5 years.“You look familiar kid, where’s your mom?”“Obviously, I look familiar, some parts of my face you see when you look in the mirror.”
Relationships: Implied Sawamura Daichi/Sugawara Koushi - Relationship, Iwaizumi Hajime/Oikawa Tooru
Comments: 8
Kudos: 291





	Children Know Better

**Author's Note:**

> Hi!
> 
> Um, I just wanted to write Tobio as Iwaizumi and Oikawa's kid....
> 
> that's basically how this story came to life.
> 
> I just love Tobio as a kid, I wish there were more fics with that, so yeah this is my contribution to that. if anyone ever has an idea with him as a kid, feel free to comment it, i'll write something
> 
> yes that's how much i love Tobio as a kid.
> 
> anyways hope you enjoy!!!
> 
> \--Max--

**_This means they are speaking English._ **

_This means they are speaking Spanish._

Anything else means Japanese.

Iwaizumi was born a beta. His scent was dull, though a lot of people said that when they caught a whiff of it, it would remind them of a mix of an omega and an alpha scent, mixing between sweetness and spiciness. His best friend, Oikawa, was born an alpha. Though his appearance was more on the slim side when they were younger, he grew into his musky scent, with enlarged shoulders and probably as much muscles as Iwaizumi. Iwaizumi had been a bit angry at that, since he kept on trying to get over him since elementary school, only for the other to grow into himself, making Iwaizumi realize how well they could fit together.

The first time he realised he had a crush on his best friend was when he had the realization that he loved smelling the other on his clothes, and that every new item of clothing had to be scented by Oikawa. That had been in elementary school. When Iwaizumi had smelled Oikawa’s first rut back at the end of their third year of middle school, it had taken him weeks to get over how much he had been aroused at the memory of his scent. But even though his attraction started with Oikawa’s scent, he fell in love with his best friend’s personality. He loved the way the other could go from acting like a child to being serious about Iwaizumi’s wellbeing; he loved how he never was one to order someone else; he loved when the other acted the way he wanted to, clinging onto Iwaizumi without a care in the world; he loved how he could also act like an alpha, spreading his pheromones when angry or frustrated, making everyone else suddenly remember his status. Iwaizumi Hajime just loved Oikawa Tooru. Unfortunately, he knew he wasn’t the other’s type.

He knew he loved soft omegas or betas, he loved a person with soft features, who loved being pampered. Iwaizumi was far from it. He had always looked a bit rough, his features were strong, and he usually didn’t like to be pampered, with Oikawa least of all as he was always the one to buy him things or let him hang onto him without too much of a fight. Iwaizumi knew all that, and yet when the opportunity came to be held by Oikawa, he took it.

Oikawa went into rut suddenly at the end of their third year of high school, when both their families weren’t home. Iwaizumi had immediately called Oikawa-san to know what to do, only to learn that Takeru just started his first rut and they were all in the hospital. She asked how far along he was, and when she learned Iwaizumi had been trying to contact her for the past two hours, she told him he had to get away before they did something they would regret. She explained that her son needed to either be confined in the hospital or to have a partner, but since he was already two hours deep into rut, the only other option was to lock him inside his house alone. Iwaizumi had at first taken a few water bottles to Oikawa’s room along with some food, and was going to leave, but he had smelled a bit of the other’s scent and hadn’t resisted the temptation to smell more. He had opened the door to Oikawa’s room, only to be pounced on by the other. He then spent the next two days with Oikawa, helping the other through his rut. When he finally was out of it, Iwaizumi proceeded to hide any evidence that he had been there, by airing out the room and spraying something to get rid of any lingering scent. Oikawa was clueless since a mate less alpha usually never remembered anything from a rut.

What Iwaizumi didn’t expect was to suddenly realise how he was slowly gaining weight and feeling a bit under the weather. When going to a doctor, on his own at to not scare anyone, they had done a few tests, only for him to be told he was pregnant. He immediately made the decision to hide his baby from everyone else. He knew Oikawa was going to leave for Argentina, he knew telling him about the baby would make him stay, but Iwaizumi didn’t want to take him away from his dream. He wasn’t going to tell his parents since he knew they would want to know who the father is, and they would talk about it with Oikawa’s parents, probably making them realise Oikawa was the father, which would eventually lead to Oikawa staying. So, Iwaizumi decided he was going to go to America like his original plan, but instead of studying, he would get a job to make sure to have enough money. He then realised that Oikawa could come randomly to visit him, so he decided to disappear to Mexico, where he gave birth to an omega boy, calling him Tobio.

Five years had passed since he gave birth to Tobio. He never ceased contact with his family, but he never went back to Japan either. He had lost contact with Oikawa after the first year, when they got into a huge fight after Iwaizumi refused to give away his location. He had continued to follow his career though, always up to date with his achievements and watching all his matches live. Tobio had grown up to be a genius, having an IQ way too high for a five-year-old kid. He understood everything about their situation, and had no problem being trilingual, speaking English, Spanish, and Japanese. Hajime decided that they needed a vacation from their busy life, with him working as a translator for a big firm, and Tobio having classes online to make up for classes at his primary school being insufficient for a kid like him. They decided on going to Brazil, as Tobio wanted to either go there or in Argentina, which wasn’t a tough choice for Hajime to make.

They arrived in Brazil, exhausted from their long flight, and immediately went to their hotel. When they arrived, Iwaizumi saw a lot of people seemed to be waiting for someone, probably for a celebrity, but didn’t think much of it. Stupid idea. They checked in and slept for the better part of the day. They decided on eating in, calling room service. The next morning, Hajime and Tobio ate breakfast and stepped outside their hotel to go to the beach. Hajime wore a cap and sunglasses, along with a scent blocker, as to always be on guard in case an alpha tried something by smelling the sweetness of his scent. They wore matching outfits, both wearing the same pair of shorts which were of the same teal colour as Aoba Johsai’s. Hajime had been playing a bit of volleyball with Tobio when another ball suddenly flew towards them. Hajime had just enough time to run towards Tobio to get the ball to hit on his back instead of Tobio’s head.

“ _Mama! Are you okay?! Mama, a bruise is forming, should I call the ambulance- “_

“ ** _I am so sorry! Is everything ok sir?”_** the voice of a man could be heard behind Hajime’s back. He turned around and saw a man probably around the same age as him holding onto the ball which had hit him in the back. He could smell the distinctive scent of two distressed omegas, one he identified as Tobio’s and one he probably thought belonged to the man in front of him. He didn’t want to cause a big deal, so he decided it was better to lighten their concerns.

**_“Ah I’m fine just a light bruise don’t worry about it,_ ** _don’t call an ambulance, a bruise is nothing ok?”_

**“ _Oh, thank god!_** Ah, Daichi! They said everything is fine, but we should still move just in case since he has a child.”

“Ok let’s go. **_Ah, really sorry again.”_**

Hajime had stopped functioning. He could smell on the omega a scent which had brought him love. He knew he had to get Tobio out of here before investigating where he was. He turned where Tobio was only to realise he wasn’t beside him. He stopped breathing and immediately started looking around. He turned where the omega and alpha were, only to see Tobio hit Oikawa in the shin.

He ran towards him, hearing the tail end of the conversation.

“ _You smell bad, but he said you always smelt good so that’s so weird. Also, why do you smell like an omega? That’s so disrespectful- “_

_“ **I am so sorry!”**_ Hajime ran over and picked up Tobio, effectively shutting him up by pressing his nose towards his scent gland, calming him to the point of making him sleepy. Hajime bowed towards Oikawa, changing his voice a bit in the hopes of not being recognised. While down, he could see Tobio had hit Oikawa’s good leg, even though he knew Tobio had known about his injury. He tried coming up with an excuse and figured telling the truth while omitting certain details could work.

**_“My son probably thought you were his father, you look a bit like him and smell a bit like him, I’m really sorry for him hitting you!”_** Hajime could see Suga and Daichi had also ran over, with an orange-haired kid following them. He hoped Tobio could stay hidden, but he could smell his scent turning a bit sweet, so it was a sign he was starting to fall asleep.

Oikawa looked at him, frowned a bit, before Suga and Daichi started speaking to him lowly. Hajime could only hear they were talking in Japanese, but he had no clue what they were saying. He looked down to avoid looking at Oikawa as much as possible, when the orange-haired kid was suddenly right by his left leg, looking up at him. He blinked and tried smiling to appease him, only for him to frown and suddenly grab Tobio’s leg which had been used to kick Oikawa. Hajime didn’t even have the time to blink before he started smelling Tobio’s anger. He knew what was going to happen, so he immediately stepped back, making Tobio miss hitting the kid in the face by a few centimetres.

_“Tobio! Don’t hit random kids in the face- “_

_“Mama he grabbed my foot!”_

_“Probably because you tried to hit someone he knows! Tobio, I’m going to put you down and you’re going to apologise.”_

_“I’ll apologise to him but I’m not apologising for hitting – “Tobio_ didn’t finish his sentence when he suddenly smelt Oikawa’s aggravated scent. Hajime had once been used to it, but since it had been a while since confronted by it, even he was a bit affected. He could feel Tobio shake a bit though, and his mother instincts kicked in, turning his son’s head towards his neck, and growling at Oikawa. His smell immediately lessened, and he could see a trace of guilt in his eyes. Hajime sighed a bit, hoping he could get this over with so he could go calm Tobio down in their hotel.

**_“I’m sorry for my scent, I tend to forget how kids are affected by it. Look, I guess I accept your apology, but the kid needs to apologise to Shouyou, that kick could’ve seriously hurt and he’s a bit scared.”_ **

God it had been years since hearing his voice in real life. They talked on the phone before they lost contact, and Hajime had watched every interview of his that he could find, but he never realised till now how much he missed it. He only nodded at the other and turned towards Tobio. Tobio was frowning at Oikawa but still looked down at the other kid, Shouyou.

“I’m sorry. I was just a bit angry; I didn’t mean to try and hurt you seriously.” Shouyou and Oikawa both looked surprised at Tobio suddenly speaking Japanese, making Hajime curse in his head. He knew how Oikawa was, and he could already see the other looking at Tobio in wonder. Tobio had spoken in Spanish to Oikawa first, seemed to understand English since he apologised without Hajime telling him to in another language, and could even speak in Japanese. Hajime knew he had to get out of here. Now.

“Oh! No worries! I didn’t think you were going to hit me, so I didn’t really get scared ha-ha!”

Now that the kid had accepted Tobio’s apology, Hajime was dead set on leaving. Nothing could stop him-

“Since your son speaks Japanese, I assume you can too? If you want to join us when you come to this beach to play volleyball, you’re invited! We Japanese who speak Spanish should stick together!” Ah fuck. Hajime could feel his heart beating. He could smell Oikawa was playing with his scent, making it a bit softer smelling as to smell as inviting as possible. Hajime smiled a bit even though he knew it must look weird with the rest of his face hidden away.

“Ah if we come here and see you, we will happily accept your invite. I have to go now though; my son seems to be too tired to continue playing today- “

“ _Mama, can we go to the hotel so I can look at the setting videos again?”_

_“Ah, of course Tobio._ Um, please to meet you, and sorry again.” Hajime didn’t let Oikawa say anything else, as he practically ran towards his belongings to be as far away from him as possible. He was going to go home and look in which hotel Oikawa was staying in, and to search for a beach further away.

He’s staying in the same hotel. The celebrity the fans were waiting for yesterday was Oikawa. He was going to have to either book another hotel or use an omega friendly taxi to go to another beach. He sighed, looking at Tobio who was by the balcony open door, watching videos of Oikawa setting. He was going to walk towards him when he heard a high pitch voice calling out to Tobio. He walked a bit towards him, only to see the kid from earlier on Oikawa’s shoulder, waving at Tobio.

Now they knew they were staying in the same hotel. This was a mess.

“Mama, shouldn’t you stop wearing a cap? You’ll lose your hair at this point.”

“Tobio, mama is trying to hide from your papa, remember? If I don’t wear a cap, he’ll find out about who you are, and there could be severe repercussions ok? Just, I’m sorry that I can’t find the courage to tell him about the both of us- “

“Mama is the bravest. Mama went to a whole other country on your own. Then you had me without anyone knowing!”

“Tobio, can you promise not to tell your papa about any of this? Thank you for calling me brave, I’ll make sure to tell him about you soon ok?”

“Ok mama, I won’t tell him anything.”

_“do you want kids?”_

_“um, little Tobio, why Spanish?”_

_“Because I grew up in Mexico, I prefer speaking Spanish. Now, do you want kids?”_

_“I guess I wouldn’t mind a kid, no. I always wanted one, but I was never in a couple with the one- “_

_“what if I was your kid? Would you like me as your son?”_

_“I wouldn’t mind, but hasn’t your mama established I’m not your father- “_

“Ask me what my last name is please. Then you must look at me and seriously think about my features. Then depending on what you understand I’ll give you the card to my mama and I’s room.”

“Japanese again, uh? Ok Tobio-chan, what’s your last name?”

“Iwaizumi. My last name is Iwaizumi.”

Hajime had been sleeping when the door to his hotel room suddenly banged open. He immediately turned towards Tobio’s bed, only to see it empty. He jumps up and right before going towards the hallway leading towards the door, he smells it. The deep anger and betrayal, along with hints of relief. He knows before looking who suddenly stepped into his room. Oikawa stood there, holding onto a key card, panting as though he had run here. He holds up a hand to stop Hajime from talking.

“Before you start, Tobio is staying with Suga, Daichi and their son Shouyou. I trust them with my life, so I trust them with my son. My son, whom you’ve hid from everyone. He didn’t tell me anything, I asked his full name, and I just had to look at him to know. Were you going to wear a stupid cap for this entire trip to hide from me? Hajime, I honestly thought you died, if not for your parents texting me every time, they received an update from you. No one knew where you were, we just knew you were suddenly a translator for a firm or something. We also knew you didn’t even go to university- “

“Tooru. We should sit- “

“When did we fuck? When did we fuck for us to conceive Tobio? Fuck I should’ve figured it out when hearing his name. I remember telling you if I had an omega son, I wanted to name him Tobio- “

“Your last rut before leaving for Argentina. I was with you when it started, and I did something stupid. I was going to lock you in your room, but I opened the door, and the rest was history. I wasn’t going to tell you because I knew going to Argentina was your dream. I didn’t want to hold you back- “

“I HAVE A SON! I DON’T FUCKING CARE ABOUT VOLLEYBALL! I had a son, and I DIDN’T EVEN KNOW! I didn’t get to see you pregnant with him, I didn’t see his birth, wasn’t there for his 5 birthdays because you took that choice for me!”

“Tooru, sit down.”

“DON’T TELL ME WHAT TO DO- “

“TOORU CLOSE THE FUCKING DOOR AND SIT THE FUCK DOWN!”

Oikawa slightly calmed down enough to close the door and sit on the bed Hajime had previously been on. Hajime sat on the floor on the opposite wall, looking at Oikawa slowly breathe in and out. He suddenly grabbed the pillow Hajime had used and smothered himself with it. Hajime could smell Oikawa suddenly calming down, and he could see his posture was growing less stiff by the second. After a minute, he dropped the pillow and looked at Hajime.

“Why call him Tobio?”

“Because you wanted your first omega son to have that name.”

“Was it like a way to feel less guilty about not telling me?”

“It was because when you said the name Tobio, I knew I wanted to name my kid that too.”

“That would’ve been weird- “

“Don’t make me say it, Tooru, you aren’t clueless.”

“Hajime, I seriously don’t know why that wouldn’t be weird- “

“Because I could see myself holding onto Tobio with you by my side, that’s why.”

Tooru looked confused until he suddenly realised what Hajime was saying. He looked down. He looked up again, and suddenly his eyes were determined.

“Hajime. I spoke with Tobio and learned where you work. Ask to be moved to Argentina. Tobio has online classes, so no matter where he is it’s fine. You can live with me until we can get a house. Then we’ll go all three of us back to Japan to show off Tobio to our families. I’m going to take responsibility; you owe me that right.”

“Tooru, I’m not going to be with you just because we have a kid- “

“No, you’re going to be with me because I am fucking in love with you even though you’re stupid enough to hide something which could’ve been the thing that could’ve pushed us to admit our feelings years ago. Now get over here so we can make out for a bit, after all you remember everything from my rut, I have no memories whatsoever.”

Hajime was crying and laughed at Tooru’s last sentence. He got up and sat on his lap, looking down at him.

“Guess we’ll just have to make some new ones then.”

“Papa look at what came through the mail! Apparently, Ojiisan and Obaasan had old pictures of you and mama from your childhood!”

“Ah those are really cute Tobi! When you guys move to Argentina, I promise to take as many pictures of you as I can for your future children!”

“Ew, papa, I’m too young to think about having a child!!”

Even though Hajime and Tobio had wanted to immediately move to Argentina, Hajime’s work wanted him to finish a project due in Mexico before being granted a position in Argentina. Hajime and Tooru still wanted to tell their parents though, so when they were still in Brazil, they video called their families to explain. Hajime’s parents had been furious at Tooru for not knowing his ruts’ schedule, while Tooru’s family had been furious at Hajime for keeping their son away from him for so long. Both had apologised after seeing how happy the family of three were and had taken to sending gifts as much as possible to Tobio. Tobio had immediately taken to calling Tooru “papa” which had made him cry the first few times.

Hajime and Tooru had a long talk, where they realised, they had both loved each other throughout their whole lives. Hajime had been sad to realise he could’ve just followed Tooru in Argentina instead of keeping Tobio a secret, while Tooru had been sad he hadn’t had the courage to confess to Hajime before leaving for Argentina. They had been having online dates to make up for lost time, and knew they were going to see each other soon.

When Hajime and Tobio arrived at the airport of Buenos Aires, they could both smell Tooru’s scent when he saw them. Tobio ran over and jumped in his arms, both sobbing at finally reuniting. Hajime had walked over and when he got close, enveloped both in his arms. Tooru smiled at him over Tobio’s shoulder and Hajime melted, scenting both of his favourite people. He could see a few people taking pictures, probably realising who Tooru was, but at that moment, he didn’t care. He had his family in his arms, and that’s all that mattered.

“You know, you might’ve probably been able to hide from me back in Brazil had it not been for Tobio running to me the moment he realised you were asleep back in the hotel.”

  
“Yeah, we are truly blessed with an intelligent child.”

“well, children know better when it comes to family I believe.”

**Author's Note:**

> I hope you enjoyed reading!!!!
> 
> I didn't write the smut cause I'm not like good enough for that, nor did i write the makeout scene. but maybe one day I'll randomly add a chapter with the smut.
> 
> idk
> 
> anyways comment if you want, I just hoped you liked it!!!!
> 
> \--Max--


End file.
